With the proliferation of the Internet in recent years, various services related to Internet streaming are provided such as IPTV (Internet Protocol TeleVision) for distributing videos, for example, by using IP (Internet Protocol). As a move toward standardization in Internet streaming, methods applied to VOD (Video On Demand) streaming and live streaming by HTTP (HyperText Transfer Protocol) streaming are being standardized. A MP4 file format is a highly promising format for container layers.
When subtitle data is stored as a component of a stream, a subtitle is displayed based on a file which stores the subtitle data (for example, see Patent Literature 1).
Utilizing TTML (Timed Text Markup Language), which has been standardized by W3C (World Wide Web Consortium), is becoming a standard for displaying subtitles. The TTML of the W3C is being increasingly adopted by other standardization organizations, and has received attention as a Timed Text-based promising format.
It is said that TTML is an XML (Extensible Markup Language) document, and thus it takes a relatively long time for processing. Thus, when an XML document is applied to live streaming, chunked TTML document instances, which are continuously generated as fragments in a short time, must be processed in real time, and so an idea needs to be implemented in a format or a processing system.
For this reason, at the present, it is considered that a TTML storing method for enabling real-time processing is indispensable in DASH (Dynamic Adaptive Streaming over HTTP) which is a prospective standard for an adaptive streaming format and in MP4 which is the main file format for streaming.